Biologic properties of human herpesvirus 7 strain SB.
The growth characteristics of human herpesvirus 7 strain SB (HHV-7 (SB)) were studied in human umbilical cord blood lymphocyte (CBL) cultures. The virus has approximately a 4-day growth cycle, as measured by immunofluorescence analysis, quantitation of the relative viral DNA concentration, and examination of infected cells by electron microscopy on consecutive days post-infection. By systematically varying the culture media components, improved culturing conditions were established. Activated lymphocytes were required for virus growth. HHV-7(SB) grew best in phytohemagglutinin-stimulated CBL cultured in media containing 0.01 mg/ml hydrocortisone. Addition of recombinant human interleukin 2 (IL-2) at concentrations exceeding 1-10 U/ml inhibited virus growth in most CBL cultures. Addition of exogenous IL-2 to the culture media had no effect on viral DNA production. However, the percentage of virus antigen-positive cells was highest when 0.1-1 U/ml was added to the media. Differences in the ability of individual CBL cultures to replicate HHV-7(SB) was not explained by differing CD4+ cell concentrations. However, individual cultures varied in the level of endogenous IL-2 production, which may contribute to the virus growth variability in CBL. HHV-7(SB) grew in the CD4-positive T-cell line SupT1, but not in a variety of other lymphocyte, fibroblast, or epithelial cell lines. Nine compounds were tested for antiviral activity against HHV-7 in vitro. Phosphonoformic acid inhibited virus growth with a 50% effective concentration of 4.8 microM. Ganciclovir (200 microM) and phosphonoacetic acid (100 microM) inhibited more than 90% of virus production. None of the compounds were cytotoxic at concentrations which inhibited the virus. A generalized increase in host cell protein synthesis was also observed in virus-infected cells similar to that seen in CBL infected with human herpesvirus 6.
Black
J B
JB
Centers For Disease Control and Prevention, Atlanta, GA 30333, USA. JXB1@CDC.GOV
Burns
D A
DA
Goldsmith
C S
CS
Feorino
P M
PM
Kite-Powell
K
K
Schinazi
R F
RF
Krug
P W
PW
Pellett
P E
PE
D000328:Adult; D000998:Antiviral Agents / Q000494:pharmacology; D018929:Cell Culture Techniques / Q000379:methods; D002460:Cell Line; D002478:Cells, Cultured; D005312:Fetal Blood; D016199:Herpesvirus 7, Human / Q000187:drug effects / Q000254:growth & development* / Q000648:ultrastructure; D006801:Humans; D008214:Lymphocytes; D008826:Microbial Sensitivity Tests
D000998:Antiviral Agents